Cadillac XT6 Engine Cuts Out Due to Start-Stop Failure

Having dealt with a similar issue on my 2017 Cadillac XT5, I can share my experience as someone with moderate car repair knowledge. The symptoms you describe strongly point to a battery issue affecting the idle stop system. My car showed identical behavior, unusual shutdowns and inconsistent start-stop functionality. The starter motor would sometimes struggle, especially during idle stop operations. The workshop diagnosed it using battery testing equipment and found my car battery was severely degraded, affecting the eco mode and idle stop features. These systems require a healthy battery to function properly. The fix involved: Complete battery diagnostics, Replacing the main car battery, Resetting the vehicle computer systems, Testing the idle stop functionality Total cost was 290€ including parts and labor. Since the repair, all systems have worked flawlessly. To provide more specific guidance, could you share: Current battery age, Whether you use short trips or longer drives, If the warning light appears consistently, Whether you notice any starter motor sounds when these issues occur This information would help determine if your case matches what I experienced.

Thanks for the detailed reply. Checking my service history, my last maintenance was just 2 months ago at 92910 KM. They actually tested the car battery during that service and said it was fine. The warning light is now appearing more frequently, usually after 10-15 minutes of driving. The start-stop system fails about half the time I come to a stop. The engine stalling happens out of nowhere), sometimes on highways, sometimes in city traffic. I've noticed a slight buzzing sound from the starter area right before these issues occur. Think I'll need a more thorough diagnosis since the automatic restart problems seem more complex than just a battery issue.

Based on your description and my similar experience with the XT5, this sounds more like an issue with the starter motor system rather than just the battery. After my initial battery replacement, I actually encountered similar symptoms that persisted, the buzzing sound you mentioned is particularly familiar. The extended diagnosis on my car revealed a failing starter motor that was causing intermittent engine stalling and disrupting the automatic restart function. The starter would sometimes engage partially, creating that buzzing sound you described, before failing to properly restart the engine. The repair involved: Replacing the starter motor assembly, Testing the eco mode and start-stop system, Recalibrating the engine control module The total repair cost was 580€, but it completely resolved both the engine stalling and warning light issues. The hybrid vehicle systems now function perfectly, including the automatic restart feature. Since your battery tested fine during recent maintenance, I would recommend having the starter motor system checked. The symptoms you describe, especially the buzzing sound and timing of the failures, match my secondary issue exactly.

The diagnostic details you shared match my situation perfectly, especially the buzzing sound issue. Im convinced now that my problem goes beyond a simple car battery issue and likely involves the starter motor, which explains why the automatic restart feature is acting up. Will schedule a full inspection focusing on the starter motor system since the engine stalling and start-stop system problems seem identical to what you experienced. The timing of failures after 10-15 minutes and that distinct buzzing sound really line up with your case. The cost estimate of 580€ helps set my expectations for the repair. Its pricey but worth fixing properly to avoid continued engine stalling issues and get the automatic restart working reliably again. Thanks for sharing your repair experience, helped me narrow down the likely cause and saved me from unnecessarily replacing a healthy battery first.